Economic considerations dictate that heavy oils or residua obtained during petroleum refining be upgraded to distillate fractions of higher economic value. It is desirable to convert bitumen or heavy crude oils to synthetic crude oils of lower boiling point so that they may be processed in conventional downstream operations. This may be carried out by hydrogenation of these materials at high temperature and high pressure. Typically this is carried out in an ebullated bed wherein the upflowing liquid charge contacts the catalyst which may be present in the form of extrudates of diameter of 0.7-1.6 mm.
Those skilled in the art have attempted to improve the catalyst systems used in the various processes for hydrogenation of heavy oils. Typical of prior art attempts to develop improved catalysts may be noted the following:
U.S. Pat. No. 4,657,665 discloses a catalyst of high macroporosity. The Total Pore Volume (TPV) is 0.85-1.5 cc/g; 0.15-0.40 cc/g of the Total Pore Volume is contained within pores having a diameter of 1200A or greater. The final composition contains VI B metal (as oxide) in amount of 3.5%-5%.
U.S. Pat. No. 4,395,328 discloses a catalyst wherein at least 0.8 cc/g of the TPV is contained within pores having a diameter of 0-120A and at least 0.1 cc/g is contained within pores having a diameter of 1200-50,000A.
U.S. Pat. No. 4,328,127 discloses a catalyst in which 40%-75% of the TPV is contained within pores having a diameter of 150A-200A and up to 5% of the TPV is contained within pores having a diameter greater than 1000A.
U.S. Pat. No. 4,309,278 discloses a catalyst in which not more than 0.2 cc/g of the TPV is contained in pores of diameter greater than 400A.
U.S. Pat. No. 4,306,965 discloses a catalyst characterized by pore volume, surface area, and pore diameter.
U.S. Pat. No. 4,297,242 discloses a catalyst wherein at least 95% of the TPV is contained in pores having a diameter less than 130A.
U.S. Pat. No. 4,225,421 discloses a catalyst wherein 3-30% of the TPV is contained in pores having a diameter greater than 600A.
U.S. Pat. No. 4,089,774 discloses a catalyst wherein at least 45% of the TPV is contained in pores having a diameter of 30-150A and at least 10% of TPV is contained in pores having a diameter of at least 300A.
U.S. Pat. No. 4,082,695 discloses a catalyst wherein at least 5% of the TPV is contained in pores having a diameter of at least 500A.
U.S. Pat. No. 3,630,888 discloses a catalyst wherein 20%-80% of the TPV is contained in pores of diameter less than 100A, 10%-40% of the TPV is contained in pores of 100A-1000A, and 10%-40% of TPV is contained in pores of diameter greater than 1000A.
It is an object of this invention to provide a catalyst of improved properties. Other objects will be apparent to those skilled in the art.